* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    height: 100vh;
    background-color: #f5f5f5;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    overflow: hidden;
}

canvas {
    border: 2px solid steelblue;
}

.toolbox {
    background-color: steelblue;
    border: 1px solid slateblue;
    width: 804px;
    display: flex;
    padding: 1rem;
}
.toolbox>* {
    background-color: #fff;
    border: none;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    height: 50px;
    width: 50px;
    margin: 0.25rem;
    padding: 0.25rem;
    cursor: pointer;
}
.toolbox > *:last-child{
    margin-left: auto;
}